1. Field of the Invention
The present invention relates to a dispenser for substances packaged in liquid form, and more particularly intended for cosmetic, dermatological, pharmaceutical, ophthalmic, or perfumery applications. More particularly, the invention relates to a dispenser comprising a flask or tank for the substance, and a closure member having an end valve and/or a pump with an endpiece, in which the surfaces that come into contact with the active principle are designed so as to filter and treat the air that penetrates into the inside of the tank.
2. Description of the Related Art
In conventional manner, four embodiments are known that serve to guarantee that the substance contained inside the tank of a dispenser remains sterile.
In a first embodiment, the substance is packaged in a deformable, flexible bag that forms the tank and that is connected to a pump that has no air intake, commonly referred to as an "airless" pump. The pump is fixed to a rigid flask, thereby holding the flexible bag captive inside the flask. As substance is taken by the user acting on the pump, so the bag shrinks, reducing its capacity by a volume that is equivalent to the volume that has been taken out, and thus leading to the tank becoming deformed.
The drawbacks of that particular embodiment lie firstly in the presence of two packages (the bag and the flask) which increases manufacturing cost, and secondly in the unfavorable ratio between usable volume and total volume. In addition, filling and packaging operations are difficult, in particular for substances that are in the form of creams.
In a second embodiment, the substance is packaged in a cylindrical flask whose bottom is provided with a moving follower piston. As the substance is taken out via an "airless" pump, so the piston rises in the flask, thereby reducing the capacity of the flask by a volume equivalent to the volume taken out.
The drawbacks of that embodiment lie mainly in the cost of the packaging, and in its unsuitability for dispensing a liquid.
In a third embodiment, specifically intended for dispensing liquids, an "airless" pump is connected to a flask which is made of glass and which is therefore not deformable. Such "airless" pumps are capable of operating when the pressure inside the flask is at 0.5 bars, and of still ensuring that doses are regular.
The glass flasks are thus filled with a liquid to 50% relative to the total volume of the flask so as to guarantee that the pressure threshold of 0.5 bars is not reached until the flask has been emptied.
The major drawback of that embodiment lies in the unfavorable ratio between the usable volume and the total volume, and thus in the extra cost generated by the volume of the packaging.
In the fourth known embodiment, constituting the subject matter of French patent application No. 2 740 431 in the name of the same Applicant, an "airless" pump is used that is connected to a flask of a plastics material whose walls are permeable to air.
The drawback of that embodiment lies in the fact that the air passes through the wall of the flask and then through the liquid, which has the effect of slowing down the rate at which air diffuses and the speed at which the extracted dose is replaced.
If the dispenser is used intensively and rapidly, then suction builds up inside the flask and can run the risk of exceeding the operating limit of the pump.